If there's no lye, it's not soap

Soap is a chemical reaction between oils and an alkali which in the case of hard soap is sodium hydroxide (NaOH) and liquid soap is potassium hydroxide (KOH).  The amount of sodium hydroxide is very precisely calculated so that the finished soap will have no active lye remaining.  Once the oils have become soap (saponified) they are a chemically different substance.  In the same way that you can't unmake a cake, you can't unmake soap, although it can be melted in a slow cooker.  

The soap batter can be coloured with different types of colourants and scented with either essential oils or fragrance oils. And that's where the fun starts, matching colour and design with scent, and trying out new design techniques.  I love taking a practical, rather ephemeral thing such as soap and turning it into an aesthetic experience.